TITLE: GCN CIRCULAR NUMBER: 8836 SUBJECT: GRB 090117C: Suzaku WAM observation of the prompt emission DATE: 09/01/22 12:37:45 GMT FROM: Kazutaka Yamaoka at Aoyama Gakuin U M. Suzuki, M. Ohno, M. Kokubun, T. Takahashi (ISAS/JAXA), Y. E. Nakagawa, T. Tamagawa (RIKEN), H. Hayashi, E. Sonoda, M. Yamauchi, H. Tanaka, R. Hara, N. Ohmori, K. Kono (Univ. of Miyazaki), A. Endo, M. Tashiro, Y. Terada, Y. Urata, K. Onda, N. Kodaka, K. Morigami, T. Sugasahara, W. Iwakiri (Saitama U.), T. Enoto, K. Nakazawa, K. Makishima (Univ. of Tokyo), S. Sugita, K. Yamaoka (Aoyama Gakuin U.), Y. Hanabata, T. Uehara, T. Takahashi, Y. Fukazawa, C. Kira (Hiroshima U.), S. Hong (Nihon U.), N. Vasquez (Tokyo Tech.), on behalf of the Suzaku WAM team, report: The long GRB 090117C (Connaughton et al., GCN8822) triggered the Suzaku Wide-band All-sky Monitor (WAM) which covers an energy range of 50 keV - 5 MeV at 2009-01-17 15:10:40 UT (=T0). The observed light curve shows relatively strong emission from T0-6 s to T0+32 s with a precursor of about 1 min. long. The duration (T90) including the precursor is about 91 seconds. The fluence in 100 - 1000 keV was (1.18 +/- 0.11) x 10^-5 erg/cm^2. The 1-s peak flux measured from T0+22 s was 1.2 (+/-0.3) photons/cm^2/s in the same energy range. Preliminary result shows that the time-averaged spectrum from T0-78 s to T0+32 s is fitted by a single power-law with a photon index of 1.72 +/- 0.18 (chi^2/d.o.f = 14/12). All the quoted errors are at statistical 90% confidence level, in which the systematic uncertainties are not included. The light curves for this burst are available at: http://www.astro.isas.jaxa.jp/suzaku/HXD-WAM/WAM-GRB/grb/trig/grb_table.html